Dishwashing apparatus



March 23, 1965 o. A. JELLIES ETAL 3,174,439

DISHWASHING APPARATUS Filed Oct. 16.1961 2 Sheets-Sheet 1 FIG. I

27 FIG. 2

INVENTORS DAVID A. JELLIES BYJOHN D. 3 AL ATTORNEY March 1965 D. A. JELLIES ETAL 3,174,489

DISHWASHINGAPPARATUS Filed Oct. 16, 1961 2 Sheets-Sheet 2 62 as e? FIG. 6 L 54 U no v 60 c FIG. 8

FIG. 9 98 45 4o INF'LOW RATE DISCHARGE HG. 5 I RATE INVENTORS Y DAVID A.SJEL|E IES m J t JOHN D.

}-- FlLLlNG-- W A -WASH ATTORNEY United States Patent 3,174,489 DKSHWASHING APPARATUS David A. Jellies, Oconomowoc, and John D. Seal, Wankesha, Wis., assignors to General Electric Company, a corporation of New York Filed Oct. 16, 1961, Ser. No. 145,224 8 Claims. (Cl. 134-57) This invention relates to dishwashing apparatus of the type in which the articles to be washed are automatically subjected to a timed schedule including washing and rinsing operations; and in particular, the invention relates to a means whereby the operational cycle may be timed without conventional time-clock operated switches.

Presently known automatic dishwashers are controlled by a time switch in which a timer motor drives a cam shaft having a plurality of cams each associated with a switch in a circuit controlling a particular phase of the operational system. One circuit, for example, periodically closes and opens to control the motor driving a pump, impeller or other liquid circulation device; unless the mech anism is one in which a reversible motor operates a discharge pump which responds to reverse rotation, it is necessary to have a cam-operated switch periodically control the pump motor. A third switch and circuit periodically closes and opens to control a solenoid valve through which the water is introduced into the dishwasher for the washing and rinsing operations, for it is the present prac tice to open the water valve for a sufiicient period before each washing or rinsing operation to introduce the re quired amount of water into the tub, and then to shut off water flow during the actual washing or rinsing period. In other words, the operation of the conventional dishwasher controlling mechanism requires the frequent operation of a number of electrical switches, and while it may be said that this type of operational control is basically satisfactory, it is, nevertheless, the experience of dishwasher manufacturers that the cycle controlling devices are a frequent source of service troubles.

In a domestic dishwasher the same water distribution or circulation pattern is practiced for each of the washing and rinsing operations. The transition from one such operation to the next is essentially identified by a drainage interval sufiicient to permit the spent washing or rinsing liquid to be evacuated from the tub and a filling interval for admission of fresh water for the succeeding operation. We have determined that substantial advantages accrue from operating the washing/rinsing pumping system and the discharge pumping system continuously throughout the total time for the washing and rinsing operations and establishing the desired operational sequence by providing means which delay the flow of liquid to the discharge pump for a period representing the desired washing or rinsing operation. In other words, by providing that liquid is retained in the tub for a predetermined number of minutes during the operation of the liquid circulation pumping system before the liquid is made available to the discharge pumping system, the desired washing or rinsing interval can be timed without interruption of the operation of the respective pumping systems. As a corollary to this, we have determined that the operation of a dishwasher, as respects its Washing and rinsing steps, can be terminated by means which counts the number of times the discharge pump is actually discharging liquid from the tub, and opens the appropriate electrical circuit after a predetermined count has been reached.

In practicing our invention we introduce water into the tub at a controlled rate continuously during the washing or rinsing operations and by an overflow system such as a siphon, establish the desired time period before the con tinuously operating discharge pump can receive the liquid for discharge. To count the number of pump-outs we provide in the discharge system of the pump a ratchet 3,174,489 Patented Mar. 23, 1965 mechanism which advances one step each time the hydraulic pressure in the discharge piping represents full flow of liquid in the discharge line and then senses the decreasing pressure typifying the completion of the pumpout operation. In other words, the ratchet action is cocked on the high pressure condition and completed on the low pressure condition. By associating such ratchet operation with a cam which controls the appropriate energy circuit, we can terminate the series of washing and rinsing operations after the ratchet is operated the prescribed number of times.

It is advantageous to have the rate of discharge much greater than the rate at which the water is admitted into the tub, to speed the discharge and thus reduce the time interval between the individual washing and rinsing operations. With a short pump-out time it is quite feasible to have the inlet valve remain open throughout the full washing and rinsing sequence, although in some circum stances it may be desirable to interrupt the water inflow as soon as the pump-out commences and resume inflow as the ratchet system completes one operational step.

An important feature of the present invention resides in the fact that the motor which concurrently drives the water circulation pumping system and the discharge pump system is of the unidirectional type, and may be a shadedpole motor instead of the much more expensive induction motor now universally used in dishwashers of the domestic type. It is another important feature of the invention that the contacts in the switch system of the energizing circuit for the main motor operate only once during the entire sequence of operations; that is, they close at the start of the first washing operation and remain closed until the final rinsing operation has been completed. We therefore substantially eliminate wear on switch contacts and thus minimize a potential trouble source. Similarly, in the embodiment of our invention in which water is introduced continuously throughout the entire sequence, we reduce the number of times it is necessary to make and break the circuit controlling the water inlet valve. In this latter method of operation we are able to use a single switch for controlling the motor and the solenoid valve, therefore making it possible to effect cost savings even while constructing the switch with heavy duty contacts and other elements.

It is, therefore, the object of the invention to provide a dishwasher of the automatic cycling type embodying a control system which does not require a time clock and in which the number of individual circuit switches is substantially reduced.

It is another object of the invention to provide a dish washing apparatus having cycle-controlling means which operates in response to liquid pressure generated by the discharge of spent washing or rinsing liquid from the tub.

Further features and advantages of the invention will be understood from the following description of a presently preferred embodiment read in connection with the accompanying drawings in which:

FIG. 1 is a front elevational view of a dishwasher embodying the present invention, with the greater portion of the cabinet door having been broken away and the dishwasher tub and external housing being shown in section;

FIG. 2 is an enlarged view of one form of means for delaying flow of liquid to the discharge pump;

FIG. 3 is a schematic plan view showing a preferred arrangement of the single drive motor for the main circulation pump and the discharge pump;

FIG. 4- is a somewhat schematic figure of the presently preferred stepping relay which controls the energizing circuit;

FIG. is a schematic showing of an adjustable siphoning mechanism;

FIGS. 6, 7 and 8 disclose circuits showing dishwasher control circuits; and

FIG. 9 is a graph showing the relationship of washing interval to the filling interval.

Referring now to FIG. 1, the dishwasher 1 includes an external cabinet 2 within which is suitably supported a tub 3 for accommodating the articles to be washed. Pursuant to conventional practice the tub 3 is open at the front and the cabinet 2 is provided with a swing-down door 4 hinged at the bottom to be manually operable between a vertically closed position and a substantially horizontal open position. Along the inner side walls of the tube arethe upper and lower track ways 5 and 6 which respectively accommodate the upper rack 7 and the lower r-ack 8 within which the articles to be washed are placed. As is well known in the art, when the dishwasher door is open each of the racks may be drawn from the tub for the purpose of loading or unloading.

For supplying water to the tub for the washing and rinsing operations we provide a conventional solenoid operated valve, preferably having facilities providing a uniform flow rate over a wide range of water inlet pressures. Such a valve, for example, is disclosed in D. H. Halenza United States Patent No. 2,500,750, granted March 14, 1950, and manufactured and sold by the Dole Valve Company of Chicago, Illinois, the assignee of the said Halenza patent. The solenoid valve 10 is connectable to the building hot water supply system (not shown) and has a gooseneck discharge tube 11 which discharges into the tub fill tube 12 which at its bottom communicates with the tub through a side wall opening therein (not shown). It will be understood that to meet code requirements the outlet end of the tube 11 is placed at least one inch above the inlet of the fill tube 12 so as to prevent backflow of water from the tub into the tube 11.

It will be understood that means (not shown) provide for introducing detergent into the water to form the desired washing solution. It is now popular practice to provide two washing operations and We propose, therefore, to use a double detergent dispenser such as disclosed in Sharp et al. Re-issue 24,198, re-issued August 21, 1956 for Dish-washing Apparatus with Automatic Detergent Dispensing Means and assigned to our assignee herein. 7

The washing and rinsing operations are accomplished by subjecting the dishwasher to sprays or streams of liquid ejecting through a conventional rotating spray nozzle device 14- rotatably mounted on a tubular hub 15 by a suitable vertically disposed pivot 16 supported on a spider 17 which offers little obstruction to liquid flow through the hub. Pursuant to conventional practice, the spray nozzle device has a plurality of liquid ejection ports distributed over its upper surface and has, in diametrically opposed side wall portions, means such as a nozzle 13 through which liquid ejects and creates reaction forces which cause the device 14 to rotate. In this way an effective liquid spray pattern is created to subject all of the articles in the tub to a proper washing or rinsing action.

Liquid is supplied to the spray device 14 by well known means such as a centrifugal pump 20 having its inlet connection 21 in the bottom of the dishwasher tub sump 22 and its outlet 23 (FIGURE 3) communicating directly with the liquid supply hub 15. It will be understood that the inlet 21 will be suitably screened to prevent large articles of food material from entering the pump 20.

To discharge spent washing and rinsing liquid we provide a second centrifugal pump 26, vented to insure priming, by way of a tube 24 which enters any convenient place in the pump casing or discharge system. Said pump has an inlet pipe 27 arranged to receive liquid from the tub as later described, and an outlet pipe 2 8 which rises within the cabinet walls to a point at which connection is made to the plumbing waste line (not shown) of the building. As is well known, it is conventional in dishwashers of the undercounter type to have the discharge line 28 rise to a point above the maximum fill level of an adjacent kitchen sink and then to discharge by way of a suitable fitting providing an air gap, into a line connecting directly with the waste trap below the sink. It will be obvious that this detail is by way of description only, and not by way of limitation.

One of the advantages of the present invention is that each of the pumps 20 and 26 may be driven from a single electric motor 30 having a double ended shaft accommodating the impellers (not shown) of the centrifugal pumps. Because the motor is subjected to very little starting torque, operates continuously during the washing and rinsing sequence, and is not required to reverse, it is entirely satisfactory to use the inexpensive shaded pole type of motor. The entire assembly of pumps and motor may be appropriately mounted on a support plate 31 aflixed to the underside of the tub 3, as suggested in FIGURE 2. For simplicity of representation the precise manner of supporting the motor and its associated pumps has not been detailed.

In the form illustrated in FIGURES 1 and 2, the

spent washing or rinsing liquid reaches the discharge pump inlet tube 27 by way of a siphon device 32 which establishes the maximum level attained by the washing or rinsing liquid before flow to the pump 26 can take place, and yet provides for substantially complete drainage of the waste liquid from the sump 22. As best shown in FIGURE 2, a siphon device includes the vertically extending tube 33 in fixed relation to the bottom wall of the tub (as by welding or otherwise securing to the mounting plate 31) and extending upwardly into the tub to the desired operational water level. Said tube 33 'rernovably accommodates a cap 34 which may have any 'desired arrangement of radially extending vertical ribs 35 which act to support the cap on the tube, but do not interfere with the passage of liquid. A cylindrical skirt portion 36 of the cap is intended to rest upon the bottom of the sump 22 of the tub. A plurality of openings 37 and 38, respectively distributed about the periphery of the skirt and its top wall, provide for the passage of water from the tub.

In a second form of siphonic device shown somewhat schematically in FIGURE 7, a drain tube 40 telescopically receives within itself the leg portion 41 of a relatively conventional siphon loop 42. The inlet end of said loop 42 is provided with an expansion sleeve 43 biased so that it tends to extend downwardly against the wall of the sump 22, while being spaced therefrom by spacing lugs or the like 44. A wing screw 45 extending through the wall of tube 40 secures the loop 42 in an adjusted position. For example, if it is desired to increase the overflow level of the spent liquid, the siphon 42 may he slid upwardly and locked in adjusted position by the wing screw 45. Contrariwise, if the level is to be reduced, the leg member 41 is telescoped further into the tube 4% and again secured in position. In either instance, the expansion or the contraction of the terminal portion 43 accommodates this adjustment while maintaining the lugs 44 against the base of the sump.

The downstream side of the pump 26 is provided with a pressure responsive ratchet actuator shown best in FIGURE 4. Advantageously the actuator 5t may be accommodated on a bracket 52 attached to a portion of the centrifugal pump 20 or other structure which will maintain a fixed reltaionship tothe assembly of main and discharge pumps and drive motor. As best indicated in FIGURE 4, the actuator 50 comprises an insertion in a tubular discharge line 28. The discharge tube may be of rubber, secured to the ends of the actuator body portion 51 by means such as conventional tube clamps 53.

It is the function of actuator St) to sense a positive pres sure condition in discharge line 28 and to operate a device which totals a predetermined number of such pressure conditions .and thereupon interrupts the dishwasher motor energy circuit as presently described. In the illustrated arrangement of the pump-out system a volume of liquid will return to the pump 26 after the motor circuit is interrupted. This condition is used to advantage, as presently described.

The body portion 51 of the actuator St) has an open top which is closed by a diaphragm 54 of appropriate area. Said diaphragm is maintained in position by means of a vented cap 55 screwed or otherwise fastened to the body 51. An actuating system 56 suitably secured to the diaphragm 54 at its center projects slideably upwardly through an appropriate opening in the cap 55 and a matching opening in the frame 58 which provides a main supporting structure for a switch stack 60. Said switch stack is relatively conventional and includes an insulating block 61 which insulatedly accommodates a rigid fixed contact arm 62 and a flexible contact arm 63, the latter being biased so as normally to effect closure of the associated contact elements. The springable contact arm 63 terminates in a cam follower portion 64. Also the insulating block 61 accommodates the upper and lower contact structures 65 and 66 respectively, said contact structures being appropriately biased so as to normally eiiect closure of their associated contacts.

We operate the switch contacts 62 and 63 by way of a cam 67 having the diametrically opposed first levels 68 and 68.1 and the intermediate diametrically opposed second levels 70 and 76.1 The respective levels are such that when the cam follower 64 is engaged by either of the first levels the contacts of the switch arms 62 and 63 are open, whereas when the cam is rotated so that the follower 64 is on either of the second levels, the switch contacts are closed.

We operate the cam in step by step fashion by means of any conventional escapement device. An appropriate device as illustrated in FIGURE 4, comprises a rigid lever 72 pivotally mounted on the upright of the structure 58 and terminating in the escapement 73. The escapement is pivotally mounted on the end of the lever 72 and is suitably spring biased to tend to rotate in a counterclockwise direction as viewed in FIGURE 4. The escapement device comprises a first leg 74- and a second leg 75, each of which legs comes into operative engagement with a tooth such as the respective teeth 76 and 77 of a ratchet 78. It will be understood that the ratchet 78 and the cam 67 may be molded from electrical insula tion material such as nylon and that they are appropriate ly mounted for rotation about a horizontal axis by suitable bracket means 80 mounted on the base of frame 58. Also, it will be understood that the actual number of ratchet teeth '76 and '77 is selected to establish the num ber of times which the diaphragm 54 must be extended and restored by rise and fall of the fluid pressure in the actuator body 51 to eiiect the transition from cam level 68 to level 68.1. The operation of the escapement de: vice is Well understood: as the rod 56 rises under the in fiuence of positive pressure against the diaphragm 54, the escapement leg 74 will rise for engagement with the next tooth of the ratchet. When pressure against the diaphragm 54 is relieved, the downward movement of lever 72 under urging of the return spring 81 will cause escapement leg 74 to advance the ratchet until leg 75 comes into engagement with a ratchet tooth. Further downward displacement of leg 74 is halted and the ratchet and its associated cam has been stepped one interval. The transition of the cam from level 68 to level 68.1 rep resents the complete operational cycle of the dishwasher as respects its washing and rinsing operations.

Means are provided for manually starting the dish washer. In the embodiment of FIGURE 4 a start knob 83 may be mounted in an appropriate place on the cab inet structure 1 and connected to the escapement lever 72 by a Bowden wire or other flexible means 84, it being understood that said wire 84 is slideably housed within the usual flexible casing (not shown). The knob 83 is biased toward the right of FIGURE 4 by means of a coil spring 85 interposed between the casing and an abutment 86 on the knob shaft 87. It will be apparent that pulling outwardly on knob 83 will rock the escapernent lever 72 upwardly against the bias of spring 81. The escapement leg 74 is thus indexed to the next upper tooth oi the atchet and upon release of the knob 83 the spring 81 will rotate the escapement to index the ratchet and the cam to bring the cam follower 64 to the cam level "itl thus closing the contacts associated with the switch springs 62 and 63.

By way of exemplifying the operation of the dishwasher, it will be assumed that the washing and rinsing operations include two washing cycles and two rinsing cycles. The last two operational cycles subject the dishes and other articles to a rinse by clear, hot water. Such a cycle requires that there be four ratcheting operations to complete these four cycles. However, because of liquid in pump 26 remaining from a previous operation the ratchet 78 will have a total of twelve teeth, six being required to index the cam from level 68 to level 68.1 and six to return the cam to level 68. Each of said levels represents a deenergized condition of the dishwasher, as previously noted. Assuming that the dishwasher has never before been operated, in which event there would be no residual liquid within the pump 26 or the discharge pipe 28, the first operation of the machine will establish a cycle in which there would be two washes and three rinses.

It will be assumed that the dishwasher is being placed in operation for the first time; that the racks have been loaded with dishes; that the two cups of the detergent apparatus of Sharp et al. Reissue 24,198 have been filled; and that the door 4 has been closed. Closing the door will close the usual door operated switch 88, preparing the energizing circuit.

Manual operation of the knob 83 accomplishes the first step of the ratchet, as above described. This brings the cam follower 6-4 to the second level 76 of the cam, thus closing the contacts 62 and 63. Referring now to FIGURE 6, this completes the solenoid valve energizting circuit by way of lead L1, closed switch 88, conductor 90, solenoid coil 10.1 of the solenoid valve, conductor 9 1, closed contacts 65 and 66, closed contacts 62 and 63 to lead L2. Water will thereupon flow into the tub. Simultaneously, the winding of the motor 30 is energized by way of lead L1, conductors 92 and 93, closed contacts 62 and 63, to lead L2.

The washing pump 20 and the discharge pump 26 are now operating because the motor is energized, but at this stage there is no appreciable load on the motor. As the water accumulates within the tub to a level where it flows in through inlet 21 to the pump Zil, the pump eventually receives suflicient water to discharge through the hub 15 into the spray device 14- whereupon the washing operation begins. This first water circulation washes the detergent out of the first cup of the Sharp et al. detergent dispenser, forming the washing solution, as set forth in the said Re-issue patent. In the fill and operation diagram of FIGURE 9, this first washing effect takes place at water level Ql. Water continues to how into the tub at the rate suggested by the FIGURE 9 curve marked inflow rate until at the attainment of level Q2, the pump is being supplied with sufficient liquid for adequate discharge through the device 14 and return circulation through the pump inlet 21. This represents the commencement of efficient water circulation. The infiowing water has not yet risen in the tub to a level submerging the upper end of the discharge tube 33, and therefore the pump 26 is not receiving any liquid to be discharged through the outlet 28. However, at the level represented by Q-3 in FIGURE 9, overflow begins through the tube 33 and pump 26 is supplied with sutficient water to prime it, whereupon the water level discharges at a relatively rapid rate. Efficient wash liquid circulation continues until the water level returns to Q-1. It will be obvious that the discharge rate is very much faster than the inflow rate whereupon although water is continuing to flow into the tub through the valve 10, the water level in the sump quickly drops to the point of sub stantially complete evacuation. Once siphonic flow through the tube 33 begins, the pump 26 will receive water until the water remaining in the tub becomes insufficient to maintain the operation of the siphon.

As the liquid is discharged from pump 26 into the body portion 51 of the actuator 50, fluid pressure against the bottom of the diaphragm 54 lifts the diaphragm and its rod 56 to rotate the escapement lever 72 in an upward direction to cock the escapement for the next ratchet action. In the FIGURE 4 embodiment and its related circuit of FIGURE 6, the upward movement of lever 72 lifts the insulated pin 72.1, which passes freely through spring leaf 66 and bears against spring leaf 65, and separates the contacts of said spring leaves, deenergizing the solenoid 10.1. The valve closes, although the pump motor 30 remains energized through the obvious circuit. During the final stages of evacuation of water from the tub the pressure against diaphragm 54 becomes insufiicient to maintain the diaphragm raised against the return action of spring 81 and the diaphragm restores to its FIGURE 4 position, thus completing one indexing of the ratchet. This represents, therefore, the first washing cycle. As the diaphragm restores, the downward movement of escapement lever 72 causes the return of contacts 65 and 66 to closed position and reenergizes the solenoid valve to again bring water into the tub. A second similar operation of the pump occurs and the articles are subjected to a washing operation with a detergent solution. Eventually the water level again reaches the point at which a flow into the pump 26 and a second upward operation of the diaphragm 54 take place. This signals the end of the scond washing operation. The water inlet valve is again deenergized; and as the pressure is reduced against the diaphragm 54 the ratchet is again indexed and the Water valve again energized to admit water for the first rinsing operation.

Because it has been postulated that six ratchet teeth are required to effect transition from level 68 to level 68.1, this first operation of the dishwasher will result in three rinsing operations. When the dishwasher is in normal operation, however, there will be two rinsing steps, for the following reason:

It will be recalled that at the end of the final rinsing operation and the deenergizing of the main circuit, liquid will return to the pump 26 by backflow through pipe 28. It will be obvious that there will be some liquid within the body 51 of the actuator 50. When the dishwasher is again put into operation by pulling out knob 83 and letting it return, the first indexing of the ratchet will cause the follower 64 to leave level 68 and drop to level 70 as previously noted, thus permitting the contact springs 62 and 63 to close. This energizes the motor 36 and operates the pump. The immediate result of pump operation is to create a fleeting pressure situation against diaphragm 54, which rises to cock the ratchet for its second indexing. The positive pressure condition is immediately relieved against the diaphragm 54 because the pump has immediately displaced the residual water. Spring 81 returns the diaphragm to index the ratchet a second time. From then on the first wash will be represented by this second index of the ratchet; the second wash by the third index; and the two rinsing operations respectively by the fourth and fifth indexing. At the end of the second rinse, the sixth and final indexing completes the first one-half revolution of the cam, whereupon level 68.1 lifts the cam follower to open the contacts 62 and 63 to terminate the washing and rinsing operations.

The circuit of FIGURE 7 is similar to that of FI 6 except that provisipns are made for an electrical start rather than the manual operation of the escapement mechanism previously noted. The knob 83 and its associated mechanism have been eliminated in favor of a normally-open delayed action switch 94 which bypasses the contacts of leaf springs 62 and 63. Switch 94 may occupy a position on the cabinet similar to that shown for the knob 83. To delay the return to open position, the switch is equipped with any conventional dash pot or other delay device 95. The dash pot maintains the switch closed for a length of time approximating the first washing operation. Again assuming that the dishwasher has never before been operated, the user depresses switch 94 to complete the energizing circuit from L1 through closed door switch 88, to conductor 90, solenoid coil 10.1, conductor 91, the closed contacts and 66, conductor 96, bypass conductor 97, switch 94 and conductor 98 to L2. The pump motor circuit is completed from L1 through conductor 92, motor coil 30, conductors 93 and 97, closed switch 94 and conductor 98 to L2. In this operational circuit there has not yet been an operation of the ratchet in the first dishwasher operation so the contacts 62 and 63 remain open. However, the water inlet valve remains open, and the pump motor 30 remains energized because of the delayed restoration of the switch 94. This delay, as above noted, is equivalent to the length of the normal washing operation. When the overflow to the pump occurs, diaphragm action will operate the ratchet mechanism through its first index to close the contacts 62 and 63. This conditions the apparatus for operation during the succeeding cycles as above noted, whether or not the switch has at that time returned to its open position. The restoration of the switch 94 to open position need not precisely correspond to the normal end of the first washing operation. As previously, there will be three rinses.

In the circumstance that water is in the pump 26 from a previous operation, closing the switch 94 will energize motor 30, and the discharge pump will expel the water against diaphragm 54, which will expand and restore as above noted and operate the ratchet to index the cam from level 68 to level 70. This establishes a parallel energy path from the motor and solenoid, whereupon the dishwasher proceeds through its established cycle of two washing and two rinsing operations.

The circuit of FIGURE 8 is similar to that of FIG- URE 7 except that the contacts 65 and 66 have been eliminated, thus establishing an operational cycle in which the water inlet valve solenoid 10.1 remains energized concurrently with the energization of the motor coil 30. It is believed that the obviousness of the circuit makes it unnecessary to describe the operation in detail.

The flow capacity of the respective discharge piping systems connected to the discharge pump inlet should preferably be somewhat greater than the flow capacity of thedischarge piping on the downstream side of the pump 26, to insure the substantially immediate rise in discharge pressure to the certain level necessary for cocking the I ratchet.

This flow capacity differential is best accomplished by appropriately sizing the outlet piping relative to the inlet piping to the pump but if necessary or desirable, an orifice (not shown) or other flow limiting device may be installed immediately downstream of the actuator 50.

While there has been described what is at present thought to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. In a dishwasher having a tub to receive articles to be washed, valve means for supplying said tub with washing liquid, a pump for withdrawing said liquid from said tub and returning it thereto for effecting the washing of said articles, a discharge pump for withdrawing said liquid from said tub and discharging it to the exterior, motor means for operating the respective pumps, electric means etiective when energized to open said valve means and effective when deeergized to close the same, and an electric circuit for energizing said motor means and said valve operating means; the combination comprising means for closing said circuit, means responsive to the attainment of a predetermined liquid level in said tub to eiiect flow of liquid therefrom to said discharge pump for substantially complete evacuation of liquid from said tub, and means effective upon totaling a predetermined number of times during which a certain fluid pressure exists in the discharge of said discharge pump to interrupt said electric circuit to stop operation of said motor means and deenergize said valve operating means.

2. In a dishwasher having a tub to receive articles to be washed, valve means for supplying said tub with was ing liquid, means for circulating washing liquid among the articles in the tub for washing them, a discharge pump for withdrawing said liquid from said tub and discharging it to the exterior, motor means for operating the liquid circulation means and the discharge pump, electric means effective when energized to open said valve means and effective when deenergized to close the same, and an electric circuit for energizing said motor means and said valve operating means; the combination comprising means for closing said circuit, means responsive to the attainment of a predetermined liquid level in said tu'o to eiiect flow of liquid therefrom to said discharge pump for substantially complete evacuation of liquid from said tub, and means eiiective upon totaling a predetermined nurnher of times during which a certain fluid pressure exists in the discharge of said discharge pump to interrupt said electric circuit to stop operation of said motor means and deenergize said valve operating means.

3. In a dishwasher having a tub to receive articles to be washed, valve means for supplying said tub with washing liquid, means for subjecting said articles to sprays of said washing liquid for washing said articles, a discharge pump for withdrawing said liquid from said tub and discharging it to the exterior, motor means for operating said washing means and said discharge pump, electric means eitective when energized to open said valve means and effective when deenergized to close the same, and an electric circuit for conjointly energizing said motor means and said valve operating means; the combination comprising means for closing said circuit, means for accumulating liquid to a predetermined liquid level in said tub before permitting flow to said discharge pump for evacuation of liquid from said tub, and means downstream of said discharge pump and effective upon the existence of a certain fluid pressure in the discharge of said discharge pump to interrupt said electric circuit to stop operation of said motor means and deenergize said valve operating means.

4. Dishwashing apparatus, comprising: a tub to contain dishes to be washed, a valve for introducing washing liquid thereinto, electromotor means efiective when energized to operate said valve to open position and when deenergized permitting said valve to assume a closed position, means including a liquid circulation mechanism for receiving liquid from said tub and returning it thereto to wash the dishes therein, means including a pump for evacuating liquid from said tub, a motor common to said circulation mechanism and said pump to operate the same, an electric circuit for energizing said valve operating means and said motor, a switch in said circuit, an actuator for operating said switch between open and closed positions, a cam operatively associated with said actuator and having a first level for operating said switch to open circuit position and a second level 'for operating said switch to closed circuit position, means for effecting a first rotation of said cam from its first level to its second level, means for rotating said cam in step-by-step fashion through its second level to its first level, means effective upon the accumulation of a predetermined amount of liquid in said tub to effect flow of liquid to said second pump for discharge, and

1% means responsive to certain fluid pressure conditions at the discharge of said pump to effect the step-by-step operation of said cam mechanism, whereupon after number of operations of said stepping mechanism suflicient to operate said cam through its said second level, said cam restores to its first level to deenergize said electric circuit.

5. Dishwashing apparatus, comprising: a tub to contain dishes to be washed, a valve for introducing washing liqid thereinto, electromotor means eiiective when energized to operate said valve to open position and when deenergized permitting said valve to assume a closed position, means including a first pump for receiving liquid from said tub and returning it thereto to Wash the dishes therein, and a second pump for evacuating liquid from said tub, a motor common to said pumps to operate the same, an electric circuit for commonly energizing said valve operating means and said motor, a switch in said circuit, an actuator for operating said switch between open and closed positions, a cam operatively associated with said actuator and having a first level for operating said switch to open circuit position and a second level for operating said switch to closed circuit position, means for manually operating said cam from its first to its second levels to energize said pumps and operate said valve to admit washing liquid into said tub, means effective upon the accumulation of a predetermined amount of liquid in said tub to effect flow of liquid to said second pump for discharge, means for efiecting a step-by-step rotation of said cam through its second level to return to its first level, and means responsive to a certain fluid pressure at the discharge of said pump to effect the operation of said cam stepping mechanism, whereupon after a number of operations of said stepping mechanism suflicient to operate said cam through its said second level, said cam restores to its first level to deenergize said electric circuit.

6. Dishwashing apparatus, comprising: a tub to contain articles to be washed, a valve for introducing washing liquid into said tub, a solenoid effective when energized to operate said valve from a normally closed to an open position, a pump for discharging liquid from said tuh to a point of waste disposal, means for delaying flow of liquid from said tub to said pump until after a predetermined accumulation of liquid within said tub, a motor for driving said pump, an electric circuit including first and second switches in series for energizing said solenoid, an electric circuit including only said second switch for energizing said pump motor, means for initially completing each said circuit to respectively energize said solenoid and said motor, and pressure sensitive means in the discharge system of said pump to operate? said switches, said means including structure eifective upon a certain increase in pump discharge pressure to open said first switch means and to prepare said second switch means for operation to open condition and eifective upon a subsequent drop in discharge pressure to return said first switch means to closed circuit condition while operating said second switch to open circuit position.

7. Dishwashing apparatus according to claim 6, in which said means for initially completing said electric circuits include an electric circuit shunting out said first and second switches and a manually operable switch in said shunting circuit.

8. Dishwashing apparatus according to claim 7, in which said manually operable switch has means effecting a return thereof to open circuit position after a predetermined time delay interval.

References Cited in the file of this patent UNITED STATES PATENTS 

3. IN A DISHWASHER HAVING A TUB TO RECEIVE ARTICLES TO BE WASHED, VALVE MEANS FOR SUPPLYING SAID TUB WITH WASHING LIQUID, MEANS FOR SUBJECTING SAID ARTICLES TO SPRAYS OF SAID WASHING LIQUIDS FOR WASHING ARTICLES, A DISCHARGE PUMP FOR WITHDRAWING SAID LIQUID FROM SAID TUB AND DISCHARGING IT TO THE EXTERIOR, MOTOR MEANS FOR OPERATING SAID WASHING MEANS AND SAID DISCHARGE PUMP, ELECTRIC MEANS EFFECTIVE WHEN ENERGIZED TO OPEN SAID VALVE MEANS AND EFFECTIVE WHEN DEENERGIZED TO CLOSE THE SAME, AND AN ELECTRIC CIRCUIT FOR CONJOINTLY ENERGIZING SAID MOTOR MEANS AND SAID VALVE OPERATING MEANS; THE COMBINATION COMPRISING MEANS FOR CLOSING SAID CIRCUIT, MEANS FOR ACCUMULATING LIQUID TO A PREDETERMINED LIQUID LEVEL IN SAID TUB BEFORE PERMITTING FLOW TO SAID DISCHARGE PUMP FOR EVACUATION OF LIQUID FROM SAID TUB, AND MEANS DOWNSTREAM OF SAID DISCHARGE PUMP AND EFFECTIVE UPON THE EXISTENCE OF A CERTAIN FLUID PRESSURE IN THE DISCHARGE OF SAID DISCHARGE PUMP TO INTERRUPT SAID ELECTRIC CIRCUIT TO STOP OPERATION OF SAID MOTOR MEANS AND DEENERGIZE SAID VALVE OPERATING MEANS. 